William Castagna

William Castagna

Partner Architect French Dip Arch (DPLG), ARB, RIBA

William, graduated in architecture in 1991 at the University of Marseille in France and joined Foster + Partners in 1995. He has worked on the design of the Great Court at the British Museum Great, the house in Cap Ferrat in southern France, Museum of Fine Arts, Boston, and the competition winning entry for the Imperial War Museum in London. Since 2010 William has been working on Apple Park in California.


William studied architecture at the University of Marseille in France, graduating in 1991. After working for a French architectural practice, he joined Foster + Partners in 1994. Following a short period working for Denton Corker and Marshall in London, he re-joined Foster + Partners in 1995 to work on a series of schemes for London’s Imperial College.

William was made a partner in 2012. His most recent work includes Apple Park in California. Set in the heart of a natural Californian landscape, the project brings together 12,000 employees within a single building. William focussed on the design and build of the main Ring Building and the workplace fit-out.

In 1999 he began work on the renovation and expansion of the Museum of Fine Arts in Boston, later moving there in 2005 to work with the local architect for the project. As lead design architect on the construction documentation phase, he had responsibility for ensuring quality and the faithful realisation of Foster + Partners’ design concept. He worked on-site as project architect between 2007 and January 2010, overseeing the construction administration.

Returning to London later that year, William collaborated on the winning competition entry for the masterplan of the Imperial War Museum in London. This high-profile project included the sensitive refurbishment of the existing building, improved access and circulation, opening the interiors to daylight and views, and established direct links with the surrounding park.

In 1996 he collaborated on the competition-winning entry for the redevelopment of Dresden Central Station. He was also the project architect on feasibility studies for a new museum centre for the South Kensington museum district and for a performing arts centre in London’s Round House. From 1997 to 1999 he worked as a key member of the design team for the Great Court at the British Museum and subsequently worked with Lord Foster on the design of his holiday house in the South of France.

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